The pharmacokinetics of inhaled hydrofluoroalkane formulations.

To obtain the full picture of a formulation, the in vitro and the in vivo information can be looked upon as components of a "prediction bridge" where the in vitro information can be used to predict lung deposition, which in turn can be used to predict clinical outcome. This bridging concept can be used as a template to evaluate new information on emerging inhaled formulations. The concept was used to evaluate literature data on new hydroflouroalkane formulations of salbutamol and beclomethasone dipropionate (BDP). The new salbutamol hydroflouroalkane formulations seem to have properties similar to those of the old chlorofluorocarbon formulations even if the presented information on effect comparisons is limited. The first BDP hydroflouroalkane formulation is a solution formulation with in vitro properties that are quite different from those of the old chlorofluorocarbon suspension formulation. The BDP hydroflouroalkane formulation has a much greater fine particle mass, which eventually results in greater lung deposition and better clinical effect.